Electric-switch construction



Sept. 25, 1962 s, MRENNA ELECTRIC-SWITCH CONSTRUCTION 4 Sheets-Sheet 1Filed June 30, 1959 S. A. MRENNA ELECTRIC-SWITCH CONSTRUCTION Sept. 25,1962 4 Sheets-Sheet 2 Filed June 30, 1959 Fig.6.

INVENTOR Stephen A. Mrennu ATTORNEY p 25, 1962 s. A. MRENNA 3,056,009

ELECTRIC-SWITCH CONSTRUCTION Filed June 50, 1959 4 Sheets-Sheet 3 54 EDISept. 25, 1962 s. A. MRENNA ELECTRIC-SWITCH CONSTRUCTION 4 Sheets-Sheet4 Filed June 30, 1959 Fig.|O.

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m? a 4 m .m m F F VIC United States Patent 3,056,009 ELECTRIC-SWITCHCONSTRUCTION Stephen A. Mrenna, Brighton Township, Beaver County, 1a.,assignor' to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Filed June 30, 1959, Ser. No. 824,114 15Claims. (Cl. 200-144) This invention relates to electric switches ingeneral, and more particularly to arc-extinguishing devices therefor.

A general object of the present invention is to provide an improvedelectric-switch construction, which shall be highly effective ininterrupting all currents, for which the switch is rated.

Another object of the invention is to provide an im provedarc-suppressor device, which may quickly be assembled in position, andmay also be applied to previously built switches, Without any necessityfor effecting the dismantlement of such switches.

Still a further object of the invention is to provide a simple andhighly effective arc-extinguishing device involving few parts which maybe readily fabricated and quickly assembled into an operative positionon the switch.

Still a further object of the invention is to considerably increase theratings of standard switches by incorporating therewith a simplearc-extinguishing device which is readily assembled into position.

Yet a further object of the invention is to provide an improvedarc-suppressor plate construction, which may be quickly inspected, andreplaced, if necessary.

Still a further object of the invention is to provide an improvedarc-suppressor plate arrangement, in which the several parts thereof maybe quickly stamped into the desired configuration, and which may bereadily assembled into the switch.

Still another object of the invention is to provide a combinedarc-suppressor plate and operating member for an electric switch.

Further objects and. advantages will readily become apparentupon'readingthe following specification, taken in conjunction with the drawings, inwhich:

FIGURE l'is a front elevational view of an electric switch incorporatingthe principles of the present invention, the cover of the enclosedswitch being open, so that the interior of the switch may be viewed, thecontact structure being shown in the closed-circuit position;

FIG. 2'is' a side elevational view, partially in vertical section, takenalong the line IIII of the electric switch shown in FIG. 1, again'thecontact structure being shown in the closed-circuit position;

FIG. 3 is a side elevational view of one of the arc-suppressor plates,which is employed in the switch construction illustrated in FIGS. 1and'2;

FIG. 4 is a fragmentary, end view of the stationary contact structure,showing the operative position of the pair of arc-suppressor plates,withthe switch-knife-blade shown in the closed-circuit position;

FIG. 5 illustrates a side elevational view of a modified typearc-extinguishing device, which may be substituted for the pair ofarc-suppressor plates, such as shown in FIG. 3;

FIG. 6 is a top in FIG. 5;

FIG. 7 is a front elevational view of a higher-rated switch,'.similartothe view illustrated in FIG. 1, again looking into the interior of theswitch casing, with the switch casing itself omitted for purposes ofclarity. Again the contact structure is shown in the closed-circuitposition;

FIG. 8 is a side elevational view of the modified type plan View of themodification shown of-arc-suppressing device for the higher-rated switchof FIG. 7, various parts being omitted for clarity, and the contactstructure being illustrated in the closed-circuit position;

FIG. 9 is atop plan view of the relatively stationary stab contact,utilized as the stationary contact structure of the device of FIG. 8;

FiG. 10 is a fragmentary end view of the device shown in FIG. 8, takenalong the line XX thereof, the contact structure being illustrated inthe closed-circuit position, and only a fragmentary portion of thecomplete in terrupting device being illustrated;

FIG. 11 is .a side elevational view of one of the perforatedarc-suppressor plates employed in the construction of FIGS. 7 and 8;

FIG. 12 is a top plan view of a relatively stationary hinge tab contactemployed as the pivotal mounting for the switch arm of the" deviceillustrated in FIG. 8;

FIG. 13 is a side elevational View of the hinge stab contact of FIG. 12;

FIGS. 14 and 15 are side elevational and plan views, respectively, ofone of the contact blades utilized in the bifurcated switch-armconstruction illustrated in FIG. 8; and

FIGS. 16 and 17 respectively illustrate side elevational and plan viewsof a flat biasing spring employed in the switch-arm construction of FIG.8.-

Referring to the drawings, and more particularly to FIGS. l-4 thereof,the reference numeral 1 generally designates an enclosed safety-switchconstruction, which may be employed for lighting circuits, or forrelatively small motor applications.

The electric switch construction 1 generally includes an enclosing sheetmetal switch boX, or case 2, for enclosing the several pole-units of theelectric switch 1. There may be two, three, or more of the pole-units,depending upon the number of lines to be controlled from the lineconnections to the load connections. In addition, there will be aneutral terminal plate 4 to accommodate the neutral line.

As more clearly illustrated in FIG. 2, the switch box 2 has a frontcover 5, which is hinged to curled tabs 6 provided at one side edge ofthe switch casing 2. Thus, the cover 5 and the switch box 2 provide atot-ally enclosed construction for the switch elements.

The side walls 7 provide journals, or bearings 8, for.

the pivotal rotation of an'operating bail 9, one external end of whichis configured to form a manually operable handle 10, shown in FIG. 1,which may be manually operated between a pair of stop lugs 11, '12 andmay be locked in such positions, if desired.

The rear wall 49 of the switch box 2 has a plurality of mountingapertures 13, which may be employed to mount the switch casing 2 upon awall, or other desired support.

As shown in FIG. 1, aninsulating molded panel, or base 14, formed from asuitable moldable material, may beemployed to mount the several switchparts.

Mounting. screws 14a thread into tapped holes provided in the rear wall49 of the switch casing 2 and hold the molded base 14 securely into theproper position. Preferably, the insulating molded base has grooves andridges molded thereon tofixedly secure the several parts into accuratelyaligned positions. Secured to the front of the insulating panel '14 area plurality of bifurcated, contact break-jaws 15, having cooperatinglegs, or furcations 16, which converge toward each other, as moreclearly shown. in FIG. 4 of the drawings.

The night portion 17 of the contact break-jaw 15 is secured to aterminal plate 18, and also the base 14 by a center mounting screw 19.

It will be noted that contacting intermediate portions of the legs 16extend toward each other as indicated at 20 and serve to frictionallyclamp into position the switch knife-blade 21, which is preferablypivotally mounted.

The terminal plate 18 is provided with a connector sleeve 22, shown inFIG. 1, which has a side portion tapped, to accommodate a clamping screw23, which fixedly secures one end of a line connection fixedly intoplace.

The lower end of the switch knife-blade 21, as viewed in FIG. 1, ispivotally connected, as by a rivet 24, to an outwardly extending leg 25of an L-shaped mounting bracket 26, which is fixedly secured by a screw27 to the base 14. In addition, the mounting screw 27 fixedly securesinto place a fuse clip 28, adapted to support a cartridge fuse 29 intoposition.

Disposed at the lower end of the panel 14, as viewed in FIG. 1, is aload terminal plate 30, which is secured by a mounting screw 31 to thepanel 14. Also the mounting screw 31 fixedly secures into properposition the companion fuse clip 32 for the cartridge fuse 29. A secondconnector sleeve 33 is fixedly secured to the load terminal plate 30 bya mounting screw, which enters from the back of the panel 14. Theconnector sleeve 33 also has a clamping screw 34, which serves tofixedly clamp into position the end of a load connector wire, as wellknown by those skilled in the art.

The neutral terminal plate 4, previously referred to, has a pair ofconnector sleeves 35, 36, together with mounting clamping screws 37, tofixedly secure into place the ends of the neutral Wire of the controlledcircuit.

With reference to FIG. 2, it will be noted that an insulating operationarm 39 is riveted by rivets 40 to an intermediate portion of theswitch-blade 21. The insulating operating arm 39 has a notch, or slot41, to accommodate the operating bail 9. Thus, rotation of the handle10, externally of the switch box 2, will effect pivotal rotation of theoperating bail 9, and hence opening, or closing pivotal movement of theknife-blades 21, as effected by the insulating operating arms 39.

With reference to FIG. 3 of the drawings, it will be noted that asuitably configured fiber plate clip 42 is provided, and constitutes oneof a pair of cooperable arc-suppressor plate clips 42, which arepositioned as shown in FIG. 4 of the drawings. It will be noted that theouter edge of each arc-suppressor plate clip 42 is flared outwardly asat 43 to assist in guiding the switchblade 21 into proper position.

It will also be noted in connection with the arcsuppressor plate 42 thata rectangular slot, or perforation 44, is provided. The Width of therectangular slot 44, as indicated by the distance X, is just the widthof the leg, or furcation 16, of the contact break-jaw 15, so that thecontacting portion 20 of the leg 16 may extend through the perforation,or hole 44, and make contact with the side of the switch-blade 21.

Additionally, the inner edges 45 of the arc-suppressor plates 42straddle the center mounting screw 19, which biases the outer free endsof the arc-suppressor plates 42 toward each other, as illustrated inFIG. 4 of the drawings.

Preferably the arc-suppressor plates 42 are made of a suitablegas-evolving material, so that gas will be evolved during theestablishment and drawing of an are, not shown, between the switch-blade21 and the contacting portions 20 of the contact break-jaw 15. This willinsure a rapid and efiicient extinction of the established arc.

As shown in the left-hand pole-unit of FIG. 1, it will be apparent thatthe arc-suppressor plates 42 are all of one type, and may simply bereversed, as shown in FIG. 1, and snapped into position. The rectangularslots 44, which accommodate the contacting portions 20 of the legs 16 ofthe break-jaw 15 assist in maintaining the arcsuppressor plates 42 in aproper position. Preferably the arc-suppressor plates 42 are formed of agas-evolving material, such as fiber, so that during the establishmentand drawing of the are, a considerable amount of gas will be evolved.The un-ionized evolved gas will quickly effect the extinction of theestablished arc, which will be drawn, of course, between the twocooperating arcsuppressor plates 42 in the region designated by thereference numeral 46 in FIG. 4 of the drawings.

FIGS. 5 and 6 illustrate a modification of the invention, in which, inplace of employing a pair of cooperable arc-suppressing plates 42,instead, a single 'U-shaped fiber wrapper, generally designated by thereference numeral 47, is employed. Each side leg 48 of the U-shapedfiber wrapper 47 is provided with a hole, or perforation 44, which is ofthe same shape as the hole 44- in the fiber plate 42 of FIG. 3. As aresult, the modified U-shaped fiber wrapper may be inserted intoposition between the legs 16 of the contact break-jaw 15, so that againthe contacting portions 20 of the legs 16 extend, or protrude, throughthe holes 44 and make contact with the switchblade 21 in theclosed-circuit position of the device. The right-hand pole unit of FIG.1 shows the assembled construction. Preferably, the 'Ushaped fiberwrapper 47 is formed of a suitable gas-evolving material, such as fiber,which has considerable benefit during arc extinction by causing theevolution of considerable amount of un-ionized gas, as mentionedhereinbefore.

With reference to FIGS. 7-17 of the drawings, a modification of theinvention is illustrated for a higherrated safety-switch. The enclosedbox 2 for the higherrated safety-switch of FIG. 7 is not illustrated,but it may be of a type similar to that shown in FIGS. 1 and 2. Theoperating bail 9 of FIG. 7 is journalled in a manner similar to thatillustrated in FIG. 1.

Supported to the rear wall 49 of the box 2 are three suitably-moldedsupport blocks, generally designated by the reference numerals 50-52.These support blocks 5652 are fixedly secured to the rear wall 49 of theenclosing box 2 by machine screws 53. The ends of the mounting screws 53extend into tapped holes provided in the rear wall 49 of the switch box2. For the two-pole device shown in FIG. 7, it will be noted that thereis mounted upon the upper support block 50 a pair of L- shaped,relatively stationary, stab contacts 54, having laterally extendingmounting portions 55, as shown in FIG. 9. As illustrated in FIG. 8,mounting screws 55a extend through the mounting block 50 and thread intotapped holes 56 (FIG. 9) provided in the laterally extending leg portion55. A sleeve connector 57 is secured by a screw 58 (FIG. 10) to themounting plate portion 55 of the stab contact 54. Such screw alsoextends through the molded support block 50, as shown in FIG. 10 of thedrawings. A clamping screw 59 is provided to fixedly secure the end of aline connector into place.

The rotatable switch-arm, generally designated by the reference numeral60 in FIG. 8, comprises a pair of contact blades 61, each of which has aconfiguration more clearly shown in FIGS. 14 and 15 of the drawings.With reference to FIGS. 14 and 15, it will be noted that the contactblades 61 have an offset portion 62 provided intermediate the endsthereof. The contact blades 61 are placed back-to-back, as shown in FIG.7, and there results thereby a pair of bifurcated portions 63, 64 at theopposite ends of the switch-arm 60.

A pair of arc-suppressor plates 65, which is more clearly shown in FIG.11, are mounted into position, with the legs, or furcations 66 extendingthrough apertures or openings 67 provided in the sides of thearc-suppressor plates 65. The vertical width Y (FIG. 11) of the aperture67 is slightly less than the vertical height of the leg 66, as indicatedby the reference numeral Z indicated in FIG. 15, so that once thefurcations, or legs 66 are inserted through the openings 67, thearc-suppressor plates 65 are not permitted to move laterally outwardly,and are maintained in the position illustrated in FIG. 7. In effect, theplates 65 are hence locked into their proper position. Bolts 68 andwashers 69 (FIG. 8) are provided to clamp the offset the configurationof portions 62 of the switch-blades 61, together with the arc-suppressorplates 65 and additional flat springs 70, more clearly shown in FIGS. 16and 17, into a proper clamped position. The holes 71 provided in theseveral elements accommodate the shank portions of the mounting bolts68. Nuts 72, shown in FIG. 7, provide a fixedly clamped construction ofthe switch-arm 60. With reference to FIG. 7, it will be noted that thelower bifurcated portion 64 straddles a relatively stationary hinge stabcontact 73, constituting one leg of a U-shaped mounting bracket,generally designated by the reference numeral 74, and fixedly secured tothe mounting block 51 by a mounting screw 75.

FIGS. 12 and 13 more clearly show the construction of the U-shaped hingemounting bracket 74. The mounting stab contact 73 has a hole 76 (FIG.13) provided therein, through which a rivet 77 (FIG. 7) pivotallysupports the switch-arm 60 into place. In addition, a contact finger 78is provided, biased by a spring 79, encircling a mounting bolt 80. Thecontacting end 81 (FIG. 13) of the contact finger 78 cooperates with theside surface of the leg 82 of the U-shaped mounting bracket 74 tocontactingly engage the knife-blade terminal 83 of a cartridge-type fuse84. FIG. 7 more clearly shows this construction. The lower end of thecartridge fuse 84 is similarly clamped into position by a fusereceptacle, comprising an L-shaped mounting bracket, generallydesignated by the reference numeral 85, and including a spring finger 78as described hereinbefore. The spring finger 78 is similarly biasedtoward the lower knife-blade terminal portion 86 of cartridge fuse 84 bya biasing spring 79, mounting nut and bolt 80, 87 in a manner similar tothat shown in FIG. 13 of the drawings. The L-shaped mounting bracket 85has a laterally extending terminal-plate portion 88, which is mounted tothe molded mounting block 52 by a mounting screw not shown. Finally, theL-shaped mounting bracket 85 has a connector sleeve 89 and a clampingscrew 90, similar to the connector sleeve 57 and mounting screw 59illustrated in FIG. 10.

A neutral plate 91 is provided, being mounted to the support block 52 bya machine screw 92, as shown in FIG. 7. The neutral terminal plate 91has a pair of connector sleeves 89 and clamping screws 90, as heretoforedescribed in connection with the mounting bracket 85. A groundconnection 91a may also be provided.

The operation of this modification of the present invention will now bedescribed. Upon operation of the manually operable handle (FIG. 1), theoperating bail 9 (FIG. 7 accommodated in slots 93 of the arc-suppressorplates 65, eifects rotation of the several switch-arms 60, to causethereby disengagement of the legs, or furcations 66 of the contactblades 61 from the stab contacts 54. The resulting arc is drawn betweenthe lower side portions 94 (FIG. 10) of the arc-suppressor plates 65 andrapid extinction thereof is achieved in a manner similar to thatheretofore described in connection with the extinguishing device ofFIG. 1. The flat biasing springs 70 insure that the legs 66 are biasedtoward the relatively stationary stab contact 54 inthe closed-circuitposition of the device, as illusrated in FIG. 10 of the drawings. Withreference to FIG. 10, it will be noted that the inner, side-contactingportions 66a, extending through the openings. 67 of plates 65, maintainfrictional contact with the sides of the relatively stationary stabcontact 54 in the closed-circuit position. Also it will be noted thatthe side edges of the contact blades 61 are flared outwardly, asindicated at 6612, to insure a proper guiding action of the switch arm60.

It will be seenthat upon removal of the bolts 68 and nuts 72 therotatable switch arm 60 may be rapidly disassembled, and a new pair ofarc-suppressor plates 65 inserted into proper position.

From the foregoing description, it will be apparent that there isprovided an improved arc-extinguishing device associated with anelectric safety-switch of the enclosed type. The fiber arc-suppressorplates 42, 65 may be rapidly manufactured, by stamping out the desiredconfiguration from fiber sheeting. The present invention results in aninexpensive arc-extinguisher particularly adaptable for use inlight-duty safety-switches. Advan tageous features of the invention areexcellent arc-extinguishing characteristics, simplicity, and low cost.Other advantageous features of the invention are the positive alignmentof the blade and break-jaw, which are insured, which results insatisfactory operation of the switch mechanism. This results from thebeveled surfaces provided on the arc suppressor plates 42, as providedby the beveled edges 43, and on the contact furcations 66 of FIGS. 14and 15. By using a good gas-evolving material, such as fiber, andconfining the established are, it is rapidly extinguished before it hasa chance to expand, and are over to ground, or to an opposite phase.With the construction illustrated in FIG. 7, it will be noted that thearc-suppressor plates 65 may have an extended portion 95,. providing theoperating slot 93 for accommodation of the actuating bar, or operatingbail 9. This results in considerable simplicity.

With the device illustrated in FIG. 7, without the provision of thearc-suppressor plates 65, the devicev was good for less than 20horsepower rating. By the addition of the arc-suppressor plates. 65,,the rating was. increased to 30 horsepower, and passed an endurancetestof 10,000 operations.

Both of the constructions illustrated in FIGS. 1 and. 7 are simple toadd to existing lines of switches without modification. No modificationof the basic contact parts are necessary. There merely involves theaddition of the arc-suppressor plates 42, 47 or 65, depending upon theratings. It has been discovered that the arc-suppressor plates of thepresent invention are considerably cheaper than moldedarc-extinguishers, which are used on safety switches, and thearc-suppressor plates are more effective.

Although there have been shown and described particular embodiments ofthe invention, it is to be clearly understood that the same were merely,for the purpose of illustration, and that changes and modifications mayreadily be made therein by those skilled in the art, without departingfrom the spirit and scope of the invention.

I claim as my invention:

1. The combination in an electric switch of a relatively stationarybreak-jaw contact having a pair of leg portions, each leg portionhaving. an intermediate portion constituting a contact face and an outerfree end clamping portion, a pivotally mounted cooperable movable switchblade which enters between said leg portions in the closed+ circuitposition of the switch, a. pair of cooperable perforated arc-suppressorplate clips disposed between said leg portions with the contact faces ofthe leg portions pro.- tru ding through the perforations of theperforated arcsuppressor plate clips and with the outer free-endclamping portions of the leg portions assisting in clamping the plateclips in fixed position, and the are established during the openingoperation of the switch extending'between said arc-suppressor plateclips and becoming extinguished;

2. The combination in an electric switch of a relatively stationarybreak-jaw contact'having a pair of leg portions, each leg portion havingan intermediate portion constituting a contact face and a pair ofclamping portions on opposite sides of said intermediate cont-act faceportion, a pivotally mounted cooperable movable switch blade whichenters between said leg portions in the closedcircuit positionof theswitch, a pair of cooperable per,- forated arc-suppressor plate clipscomposed of a gasevolving material disposed between said legportions-with the contact faces of the leg portions protruding throughthe perforations of the perforated arc-suppressor plate clampingportions on each leg into proper poclips and with the pair of portionclamping the respective plate clip sition, and the are establishedduring the. opening-operation of the switch extending between saidarc-suppressor plate clips and becoming extinguished.

3. The combination in an electric switch of a relatively stationarybreak-jaw contact having a pair of leg portions, each leg portion havingan intermediate inwardly extending contact face portion and oppositelydisposed strap-like clamping portions, a pivotally mounted cooperablemovable switch blade which enters between said leg portions in theclosed-circuit position of the switch and into engagement with thecontact face portions, a pair of cooperable perforated fiberarc-suppressor plate clips disposed between said leg portions with thecontact face portions of the leg portions protruding through theperforations of the perforated arc-suppressor plate clips and with theoppositely disposed strap-like clamping portions of each leg portionholding the respective plate clip into position, and the are establishedduring the opening operation of the switch extending between saidarc-suppressor plate clips and becoming extinguished.

4. The combination in an electric switch of a relatively stationarybreak-jaw contact having a pair of leg portions, each leg portion havingan intermediate portion constituting a contact face and an outer freeend clamping portion, a pivotally mounted cooperable movable switchblade which enters between said leg portions in the closedcircuitposition of the switch, a U-shaped side perforated arc-suppressorwrapper disposed between said leg portions with the contact faces of theleg portions protruding through the side perforations of the U-shapedwrapper and with the outer free end clamping portions of the legportions assisting in clamping the U-shaped wrapper into fixed position,and the established arc being drawn be tween the side legs of theU-shaped arc-suppressor wrapper during the opening operation of theswitch to become extinguished.

5. The combination in an electric switch of a relatively stationarybreak-jaw contact having a pair of leg portions, each leg portion havingan intermediate portion constituting a contact face and a pair ofclamping portions on opposite sides of said intermediate contact faceportion, a pivotally mounted cooperable movable switch blade whichenters between said leg portions in the closedcircuit position of theswitch, a U-shaped side perforated arc-suppressor wrapper composed of agas-evolving material disposed between said leg portions with thecontact faces of the leg portions protruding through the sideperforations of the U-shaped wrapper and with the pair of clampingportions on each leg portion clamping the respective side Wall of theU-shaped wrapper into fixed position, and the established are beingdrawn between the side walls of the U-shaped arc-suppressor wrapperduring the opening operation of the switch to become extinguished.

"6. The combination in an electric switch of a relatively stationarybreak-jaw contact having a pair of leg portions, each leg portion havingan intermediate inwardly extending contact face portion and oppositelydisposed strap-like clamping portions, a pivotally mounted cooperablemovable switch blade which enters between said leg portions in theclosed-circuit position of the switch, a U-shaped side perforated fiberarc-suppressor wrapper disposed between said leg portions with thecontact faces of the leg portions protruding through the sideperforations of the U-shaped wrapper and with the oppositely disposedstrap-like clamping portions of each leg portion holding the respectiveside wall of the U- shaped wrapper into fixed position, and theestablished arc being drawn between the side walls of the U-shaped arcsuppressor wrapper during the opening operation of the switch to becomeextinguished.

7. An electric switch including a spaced pair of relatively stationarystab contacts, a bifurcated switch blade pivotally mounted about onerelatively stationary stab contact and making engagement anddisengagement with the other relatively stationary stab contact, a pairof co- E3 operable arc-suppressor plates attached to and movable withthe bifurcated switch blade independently of said other stab contact toextinguish the established arc, and said pair of arc-suppressor platesseparating from said other relatively stationary stab contact in thefully open circuit position of the electric switch.

8. An electric switch including a spaced pair of relatively stationarystab contacts, a bifurcated switch blade pivotally mounted about onerelatively stationary stab contact and making engagement anddisengagement with the other relatively stationary stab contact, and apair of cooperable arc-suppressor plates composed of a gas-evolvingmaterial attached to and movable with the bifurcated switch bladeindependently of said other stab contact to extinguish the establishedarc, and said pair of arc-suppressor plates separating from said otherrelatively stationary stab contact in the fully open circuit position ofthe electric switch.

9. An electric switch including a spaced pair of relatively stationarystab contacts, a bifurcated switch blade pivotally mounted about onerelatively stationary stab contact and making engagement anddisengagement with the other relatively stationary stab contact, a pairof cooperable fibre arc-suppressor plates attached to and movable withthe bifurcated switch blade independently of said other stab contact toextinguish the established arc, and said pair of arc-suppressor platesseparating from said other relatively stationary stab contact in thefully open circuit position of the electric switch.

10. An electric switch including a spaced pair of relatively stationarystab contacts, a bifurcated switch blade pivotally mounted about onerelatively stationary stab contact and making engagement anddisengagement with the other relatively stationary stab contact, a pairof cooperable arc-suppressor plates attached to and movable with thebifurcated switch blade independently of said other stab contact toextinguish the established are, an operating bar for effecting openingand closing motion of said bifurcated switch blade, and thearc-suppressor plates having slots therein to accommodate said operatingbar.

11. An electric switch including a relatively stationary U-shapedcontact jaw the outer free ends of the furcations of which are flaredaway from each other, intermediate portions of said furcations of theU-shaped contact jaw being more closely spaced together than other innerportions of the furcations of the U-shaped contact jaw, a movable switchblade adapted to enter between the outer flared-away portions of thecontact jaw and make frictional clamping engagement with said closelyspaced intermediate portions of the U-shaped contact jaw, a pair ofarc-suppressor plate clips, each of said arcsuppressor plate clipshaving a rectangular hole therein, and the pair of arc-suppressor plateclips being positioned between said furcations with said intermediatecontacting portions of the furcations extending through the rectangularslots.

12. An electric switch including a relatively stationary U-shapedcontact jaw the outer free ends of the furcations of which are flaredaway from each other, intermediate portions of said furcations of theU-shaped contact jaw being more closely spaced together than other innerportions of the furcations of the U-shaped contact jaw, a movable switchblade adapted to enter between the outer flared-away portions of thecontact jaw and make frictional clamping engagement with said closelyspaced intermediate portions of the U-shaped contact jaw, a pair ofarc-suppressor plate clips, each of said arc-suppressor plate clipshaving a rectangular hole therein, the pair of arcsuppressor plate clipsbeing positioned between said furcations with said intermediatecontacting portions of the furcations extending through the rectangularslots, a center mounting screw for holding said U-shaped contact jawinto position, and said center mounting screw having the extremity ofthe shank portion thereof extending between the inner ends of thesuppressor plate clips to bias the outer blade-receiving ends thereoftogether- 13. An electric switch including a relatively stationaryU-shaped contact jaw the outer free ends of the furcations of which areflared away from each other, intermediate portions of said furcations ofthe U-shaped contact jaw being more closely spaced together than otherinner portions of the furcations of the U-shaped contact jaw, a movableswitch blade adapted to enter between the outer flared-away portions ofthe contact jaw and make fric tional clamping engagement with saidclosely spaced intermediate portions of the U-shaped contact jaw, a pairof arc-suppressor plate clips, each of said arc-suppressor plate clipshaving a rectangular hole therein, the pair of arcsuppressor plate clipsbeing positioned betwen said furcations with said intermediatecontacting portions of the furcations extending through the rectangularslots, and the outer blade-receiving ends of the arc-suppressor plateclips being flared outwardly for proper guiding of the movable switchblade.

14. The combination in an electric switch of a relatively stationarycontact stab, at pivotally mounted switch arm including a pair ofgenerally rectangularly-shaped contact blades placed back-to-backforming an elongated generally rectangularly-shaped bifurcated portionat the free end of the pivotally mounted switch arm, said contact stabentering between the legs of said bifurcated portion in the closedposition of the switch, a pair of arcsuppressor plates secured to andmovable with said switch arm having substantially rectangular slotsprovided therein to accommodate the legs of the bifurcated portion ofthe pivotally mounted switch arm, contacting portions of said legsengaging said contact stab through the substantially rectangular slotsof the arc-suppressor plates, and the lateral width of saidsubstantially rectangular slots provided in the suppressor plates beingless than the lateral Width of the elongated generallyrectangularly-shaped contact blades so that the edge portions of thelatter will exert clamping action upon the suppressor plates.

15. The combination in an enclosed electric switch having a switch boxand an operating bail journalled in the side walls of the box of arelatively stationary contact stab, a pivotally mounted switch armincluding a pair of generally rectangularly-shaped contact blades placedbackto-back forming an elongated generally rectangularlyshapedbifurcated portion at the free end of the pivotally mounted switch arm,said contact stab entering between the legs of said bifurcated portionin the closed position of the switch, a pair of arc-suppressor platessecured to and movable with said switch arm having substantiallyrectangular slots provided therein to accommodate the legs of thebifurcated portion of the pivotally mounted switch arm, contactingportions of said legs engaging said contact stab through thesubstantially rectangular slots of the arc-suppressor plates, outer edgeportions of the arc-suppressor plates having slots provided therein toaccommodate said operating bail, and the lateral width of saidsubstantially rectangular slots provided in the suppressor plates beingless than the lateral Width of the elongated generallyrectangularly-shaped contact blades so that the edge portions of thelatter will exert clamping action upon the suppressor plates.

References Cited in the file of this patent UNITED STATES PATENTS1,521,009 Colby et al. Dec. 30, 1924 1,898,128 Jackson et a1. Feb. 21,1933 1,955,961 Jackson Apr. 24, 1934 1,993,273 Hammerly Mar. 5, 19352,116,673 Fisher et al. May 10, 1938 2,142,674 Jackson Jan. 3, 19392,325,697 Millermaster et a1. Aug. 3, 1943 2,588,195 Ballou Mar. 4, 19522,644,061 Dietrich June 30, 1953 2,654,011 Kingdon Sept. 29, 19532,840,671 Gietfers June 24, 1958 FOREIGN PATENTS 1,011,033 Germany June27, 1957 1,053,615 Germany Mar. 6, 1959

